The research project is designed to yield information pertaining to: (1) the epidemiological patterns of latent virus infections in primate tissues with special reference to cytomegaloviruses. (2) the pathogenesis and persistence of simian foamy virus infection in rabbits, and (3) the pathogenesis and persistence of cytomegalovirus in monkeys and in guinea pigs. The mechanism of viral latency, the mode of transmission and the manifestation of slow chronic diseases will be pursued further.